As a manufacturing method of this type of semiconductor wafer, there has been conventionally disclosed a manufacturing method of a semiconductor substrate (see, e.g., Patent Reference 1) by which an epitaxial film is formed on a semiconductor substrate including the inside of a trench by an epitaxial growth method and etching processing with respect to a part of this epitaxial film and film formation processing of the epitaxial film are repeated more than once to fill the superimposed epitaxial films in the trench.
In a semiconductor substrate manufactured by such a method, since an opening portion in a trench is widened by performing etching processing with respect to a part of an epitaxial film, forming the epitaxial film in this state can prevent the opening portion of the trench from being closed. As a result, it is possible to suppress occurrence of an embedding defect (a cavity) in the trench.
Patent Reference 1: Japanese Unexamined Patent Application Publication No. 2001-196573 (claim 4, Description [0042]-[0048], Description [0049].